Many people use access terminals, such as cell phones and personal digital assistants (PDAs), to communicate with wireless access networks, such as cellular wireless networks. These access terminals and access networks typically communicate with each other over a radio frequency (RF) air interface according to a wireless protocol such as Evolution Data Optimized (Ev-DO), perhaps in conformance with one or more industry specifications such as IS-856, Release 0 and IS-856, Revision A. Another protocol that may be used is known as Code Division Multiple Access (CDMA), perhaps in conformance with one or more industry specifications such as IS-2000. Other protocols may be used as well, such as Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), and/or any others.
Access networks typically provide services such as voice, Short Message Service (SMS) messaging, and packet-data communication, among others, and typically include a plurality of base stations, each of which provide one or more coverage areas, such as cells and sectors (i.e., individual areas of a cell that allow the cell to carry more calls). When an access terminal is positioned in one of these coverage areas, it can communicate over the air interface with the base station, and in turn over one or more circuit-switched and/or packet-switched signaling and/or transport networks to which the base station provides access.
Access terminals and access networks may conduct communication sessions (e.g. voice calls and data sessions) over a pair of frequencies known as carriers, with a base station of an access network transmitting to an access terminal on one of the frequencies, and the access terminal transmitting to the base station on the other. This is known as frequency division duplex (FDD). A base-station-to-access-terminal link is known as the forward link, while a access-terminal-to-base-station link is known as the reverse link. Each base station may transmit pilot signals to the access terminals via the forward link. The access terminals may use the pilot signals to determine which base station(s) to conduct the communication sessions.
In accordance with some wireless protocols, such as EvDO, each access terminal measures the signal-to-interference-and-noise-ratio (SINR) of the pilot signals received at that access terminal so as to determine a data rate at which it should receive data from the access network. In turn, these access terminals transmit to the access network data rate requests that indicate the determined data rate. The access network then transmits data to each access terminal at the data rate requested by that access terminal. Since SINR measurements of pilot signals may be used to determine data rates at which an access terminal will receive data from the access network, changes in interference and/or noise received and/or occurring at that access terminal may affect the data rate requested by that access terminal and, in turn, the rate at which that access terminal receives data via the forward-link.